如何使用 BLE OBDII 外设
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【中文标题】如何使用 BLE OBDII 外设【英文标题】：How to use BLE OBDII Peripheral 【发布时间】：2017-03-03 03:24:14 【问题描述】：我正在尝试创建一个从 OBDII 蓝牙 4 (LE) 设备读取数据的 ios 应用。我购买了 Vgate icar3 蓝牙（4.0）elm327 OBDII。我把它插到我的车里，找到了宣传某些服务的 IOS-VLink 外围设备。然后我可以获得这些服务的特征。这些是我找到的服务：
<CBService: 0x1780729c0, isPrimary = YES, UUID = Battery>
<CBService: 0x178072a80, isPrimary = YES, UUID = 1803>
<CBService: 0x178072ac0, isPrimary = YES, UUID = 1802>
<CBService: 0x178072b00, isPrimary = YES, UUID = 1811>
<CBService: 0x178072b40, isPrimary = YES, UUID = 1804>
<CBService: 0x178072b80, isPrimary = YES, UUID = 18F0>
<CBService: 0x178072bc0, isPrimary = YES, UUID = Device Information>
<CBService: 0x178072c00, isPrimary = YES, UUID = E7810A71-73AE-499D-8C15-FAA9AEF0C3F2>
但我不知道 1803、1802、1811、1804 和 18F0 服务是什么或如何使用它们。这是我的简单程序，用于找出正在宣传的内容。
class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate
var centralManager = CBCentralManager()
var peripherals = [CBPeripheral]()
@IBOutlet weak var outputTextView: UITextView!
override func viewDidLoad()
super.viewDidLoad()
centralManager.delegate = self
override func didReceiveMemoryWarning()
super.didReceiveMemoryWarning()
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral)
print("connected to \(peripheral.name ?? "unnamed")")
peripheral.delegate = self
peripheral.discoverServices(nil)
func centralManagerDidUpdateState(_ central: CBCentralManager)
if central.state == .poweredOn
central.scanForPeripherals(withServices: nil, options: nil)
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber)
if peripheral.name == "IOS-Vlink"
peripherals.append(peripheral)
print(peripheral.name ?? "peripheral has no name")
print(peripheral.description)
central.connect(peripheral, options: nil)
central.stopScan()
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?)
guard let services = peripheral.services else
return
for service in services
print(service.description)
peripheral.discoverCharacteristics(nil, for: service)
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?)
guard let chars = service.characteristics else
return
for char in chars
print(char.description)
【问题讨论】：
我发现这个关于 E7810A... uuid globals.market/offer/… 和这个 bluetooth.com/specifications/gatt/services 关于其他 uuid。还是不知道怎么用。 我有一个类似的问题，这里是答案：***.com/questions/61090365/… 【参考方案1】：我想通了。 “E7810A71-73AE-499D-8C15-FAA9AEF0C3F2”服务的特征是 uuid 为“BEF8D6C9-9C21-4C9E-B632-BD58C1009F9F”。如果您向该特征写入 AT 命令，则它会调用peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)，然后在 value 属性中获取结果。这是发送简单 ATZ 命令的代码。此时它只是使用正确的 OBDII ELM327 命令。
class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate
var centralManager = CBCentralManager()
var peripherals = [CBPeripheral]()
@IBOutlet weak var outputTextView: UITextView!
override func viewDidLoad()
super.viewDidLoad()
centralManager.delegate = self
override func didReceiveMemoryWarning()
super.didReceiveMemoryWarning()
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral)
print("connected to \(peripheral.name ?? "unnamed")")
peripheral.delegate = self
peripheral.discoverServices([CBUUID(string:"E7810A71-73AE-499D-8C15-FAA9AEF0C3F2")])
func centralManagerDidUpdateState(_ central: CBCentralManager)
if central.state == .poweredOn
central.scanForPeripherals(withServices: nil, options: nil)
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber)
if peripheral.name == "IOS-Vlink"
peripherals.append(peripheral)
print(peripheral.name ?? "peripheral has no name")
print(peripheral.description)
central.connect(peripheral, options: nil)
central.stopScan()
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?)
guard let services = peripheral.services else
return
for service in services
peripheral.discoverCharacteristics([CBUUID(string:"BEF8D6C9-9C21-4C9E-B632-BD58C1009F9F")], for: service)
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?)
guard let chars = service.characteristics else
return
guard chars.count > 0 else
return
let char = chars[0]
peripheral.setNotifyValue(true, for: char)
peripheral.discoverDescriptors(for: char)
print (char.properties)
peripheral.writeValue("ATZ\r\n".data(using: .utf8)!, for: char, type: CBCharacteristicWriteType.withResponse)
peripheral.readValue(for: char)
if let value = char.value
print(String(data:value, encoding:.utf8) ?? "bad utf8 data")
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)
if let value = characteristic.value
print(String(data:value, encoding:.utf8)!)
func peripheral(_ peripheral: CBPeripheral, didDiscoverDescriptorsFor characteristic: CBCharacteristic, error: Error?)
print(characteristic.descriptors ?? "bad didDiscoverDescriptorsFor")
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?)
if let error = error
print(error)
print("wrote to \(characteristic)")
if let value = characteristic.value
print(String(data:value, encoding:.utf8)!)
【讨论】：
【参考方案2】：如果您在https://www.bluetooth.com/specifications/gatt/services 上找到指定的服务，您可以点击服务链接获取有关特征的信息。从服务描述中，可以通过特征链接了解更多信息。
例如：0x1804 服务用于传输功率级别。它是一个只读服务，提供 org.bluetooth.characteristic.tx_power_level 特性，如果链接到该特性，可以看到它提供 -100 到 20 之间的有符号 8 位 db 级别。
另一个例子：服务 0x1811 用于警报通知服务。它提供了 5 个独立的特征，org.bluetooth.characteristic.supported_new_alert_category、org.bluetooth.characteristic.new_alert、org.bluetooth.characteristic.supported_unread_alert_category、org.bluetooth.characteristic.unread_alert_status 和 org.bluetooth.characteristic.alert_notification_control_point。服务描述为每个特性提供了简短的解释，并链接到该特性的值的更多详细信息。如果您的设备无法通过语音、SMS、IM 或电子邮件发送消息，这些特征可能没有意义，并且可能不受支持。
【讨论】：
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